/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use
 * this file except in compliance with the License. You may obtain a copy of the License at the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apereo.portal.spring.context;

import com.google.common.collect.MapMaker;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.GenericTypeResolver;

/**
 * Extension of SmartApplicationListener that allows configuration of a set of supported and ignored
 * event classes.
 *
 * <p>extend GenericApplicationListenerAdapter
 */
public class ClassApplicationEventFilter<E extends ApplicationEvent>
        implements ApplicationEventFilter<E>, InitializingBean {
    protected final Logger logger = LoggerFactory.getLogger(this.getClass());

    private final Map<Class<? extends ApplicationEvent>, Boolean> supportedEventsCache =
            new MapMaker().weakKeys().makeMap();
    private Class<?> typeArg;

    private Set<Class<? extends ApplicationEvent>> supportedEvents = Collections.emptySet();
    private Set<Class<? extends ApplicationEvent>> ignoredEvents = Collections.emptySet();

    /**
     * If no <code>supportedEvents</code> {@link Collection} is configured all {@link
     * ApplicationEvent} sub-classes are supported otherwise matching is done. The property defaults
     * to null (all event types)
     *
     * @param supportedEvents the supportedEvents to set
     */
    public void setSupportedEvents(Collection<Class<? extends ApplicationEvent>> supportedEvents) {
        this.supportedEventsCache.clear();
        if (supportedEvents == null) {
            this.supportedEvents = Collections.emptySet();
        } else {
            this.supportedEvents =
                    new LinkedHashSet<Class<? extends ApplicationEvent>>(supportedEvents);
        }
    }

    /**
     * If no <code>ignoredEvents</code> {@link Collection} is configured all {@link
     * ApplicationEvent} sub-classes are supported otherwise matching is done. The property defaults
     * to null (all event types)
     *
     * @param supportedEvents the supportedEvents to set
     */
    public void setIgnoredEvents(Collection<Class<? extends ApplicationEvent>> ignoredEvents) {
        this.supportedEventsCache.clear();
        if (ignoredEvents == null) {
            this.ignoredEvents = Collections.emptySet();
        } else {
            this.ignoredEvents =
                    new LinkedHashSet<Class<? extends ApplicationEvent>>(ignoredEvents);
        }
    }

    public void afterPropertiesSet() throws Exception {
        //Figure out the generic type's Class, cribbed from SmartApplicationListener
        Class<?> typeArg =
                GenericTypeResolver.resolveTypeArgument(this.getClass(), ApplicationListener.class);
        if (typeArg == null || typeArg.equals(ApplicationEvent.class)) {
            Class<?> targetClass = AopUtils.getTargetClass(this);
            if (targetClass != this.getClass()) {
                typeArg =
                        GenericTypeResolver.resolveTypeArgument(
                                targetClass, ApplicationListener.class);
            }
        }
        this.typeArg = typeArg;
    }

    /* (non-Javadoc)
     * @see org.apereo.portal.spring.context.ApplicationEventFilter#supports(org.springframework.context.ApplicationEvent)
     */
    @Override
    public boolean supports(E event) {
        final Class<? extends ApplicationEvent> eventType = event.getClass();
        final Boolean cachedSupports = this.supportedEventsCache.get(eventType);
        if (cachedSupports != null) {
            return cachedSupports;
        }

        final boolean supports = supportsEventTypeHelper(eventType);
        this.supportedEventsCache.put(eventType, supports);
        return supports;
    }

    private boolean supportsEventTypeHelper(Class<? extends ApplicationEvent> eventType) {
        if (typeArg != null && !typeArg.isAssignableFrom(eventType)) {
            return false;
        }

        if (this.ignoredEvents.contains(eventType)) {
            return false;
        }

        if (this.supportedEvents.contains(eventType)) {
            return true;
        }

        //Check inheritance for includes match if no explicitly matching
        for (final Class<? extends ApplicationEvent> includedType : this.ignoredEvents) {
            if (includedType.isAssignableFrom(eventType)) {
                return false;
            }
        }

        //Check inheritance for includes match if no explicitly matching
        for (final Class<? extends ApplicationEvent> includedType : this.supportedEvents) {
            if (includedType.isAssignableFrom(eventType)) {
                return true;
            }
        }

        return this.supportedEvents.isEmpty();
    }
}